This plugin allows direct editing of ePub files in an external editor such as Sigil via a right-click menu. This plugin means users now have two choices for editing ePubs, with the "non-sigil" approach being the existing "Tweak ePub" function.

Special Notes:

I have not tested this plugin on anything other than Windows. If someone running Calibre can feedback success or failure on other platforms it would be appreciated by others I am sure.

After editing the ePub, regardless of whether you make changes no information is updated in the Calibre database (such as the CRC for this file). I'm not aware of any downside to doing this and it is fairly common for users to directly edit formats of files.

Installation Steps:

Follow installation steps as per first post in this thread

Add a custom tweak value in Preferences->Tweaks reflecting the path to your editor such as Sigil. In the snippet below (Windows 7 64-bit) my path is as follows: